Chapter 25 Review
Vibrations and Waves Vibration: a wiggle in time
Wave: wiggle in space and time (Hewitt, 372) 25.1 Vibration of a Pendulum
Period: The time required for a pendulum to make one back and forth swing
Equation: t= 2Π √L/g
The longer the pendulum the longer the period, shorter the pendulum the shorter the period
25.2 Wave Description
Simple harmonic motion: The back and forth vibrating motion of a swinging pendulum.
Sine curve: A curve whose shape represents the crests and troughs of a wave.
Crest: One of the places in a wave where the wave is highest or the disturbance is greatest on the wave.
Trough: One of the places in a wave where the wave is lowest or the disturbance is greatest to the opposite crest.
Amplitude: The distance from the midpoint to the maximum crest of a wave or, from the midpoint to the minimum trough.
Wavelength: The distance from the top of one crest to the top of the next one.
Frequency: How frequently a vibration occurs
Frequency= 1/period
Period= 1/frequency
Examples:
Kaitlyn's heart beats 70 times per minute what is the period and frequency of her heart's beats? Answer: Frequency=70 Period= 1 minute
In Pittsburgh there is an unsafe building that is 500 meters high. It oscillates in the wind with a period of 4.45 seconds. What is the frequency of the vibration? Answer: 1/4.45=.225 Hz
Hertz: A unit of frequency
Source of all waves is something that vibrates
25.3 Wave Motion
When energy is transferred by a wave from a vibrating source to a receiver, there is no transfer of matter between the two points.
The energy transferred from a vibrating source to a receiver is passed by a change in a medium
The speed of a wave depends on the medium through which the wave moves.
Whatever the medium, the speed, frequency, and wavelength of the wave are related
Wave speed= frequency * wavelength
Low frequencies have long wavelengths and high frequencies have shorter wavelengths.
25.5 Transverse Waves ·Transverse wave: Whenever the motion of the medium is at right angles to the way in which a wave travels. 25.6 Longitudinal Waves
Longitudinal wave: A wave in which the vibration is in the same direction the wave is traveling.
Interference pattern: A pattern formed by the overlapping of two or more waves that arrive in the same place at the same time.
Constructive interference: The addition of two or more waves when wave crests overlap.
Destructive interference: Combination of waves where crest parts of one wave overlap through parts of another, resulting in a wave of decreased amplitude.
Out of phase: Term applied to two waves for which the crest of one wave arrives at the same place and at the same time that a trough of the second wave arrives.
In phase: Term applied to two or more waves whose crests and troughs arrive at the same place at the same time.
25.8 Standing Waves
Standing wave: Wave in which parts of the wave remain stationary and the wave does not appear to be traveling.
Node: Any part of a standing wave that remains still.
Antinodes: The positions on a standing wave where the largest amplitudes are.
25.9 Doppler Effect
Doppler Effect: The change in frequency of a wave due to the motion of the source or of the receiver. (Hewitt, 383)
Blue shift: An increase in the frequency of light from source; called this because the increase is toward the high frequency, or blue, end of the color spectrum.
Red shift: A decrease in the measured frequency of light from a withdrawing source; called this because the decrease is toward the low frequency, or red, end of the color spectrum.
The greater the speed of the source, the greater the Doppler effect will be.
The pitch of the sound is greater when the source moves toward you, and less when it moves away.
http://asms.k12.ar.us/classes/physics/GENERAL/CATHERIN/DOPPLER1.GIF 25.10 Bow Waves ·Bow wave: The v-shaped wave produced by a moving object on a liquid surface faster than the wave speed. ·Something can be supersonic if it travels faster than sound. ·Bow waves are created by a speed boat going through the water and is made by the overlapping of many waves crests. http://media-2.web.britannica.com/eb-media/95/124895-004-BDC9E53F.jpg 25.11 Shock Waves ·Shock wave: A cone shaped wave produced by an object moving at supersonic speed through a liquid. ·Shock wave is produced by overlapping spheres that form a cone. ·Sonic boom: The sharp crack heard when the shock wave that comes from a supersonic aircraft. Works Cited
Hewitt, Paul G. Conceptual Physics: With Expanded Technology The High School Physics Program. New York: Addison-Wesley Pub (Sd), 1999.
Vibrations and Waves
Vibration: a wiggle in time
Wave: wiggle in space and time (Hewitt, 372)
25.1 Vibration of a Pendulum
- Period: The time required for a pendulum to make one back and forth swing
- Equation: t= 2Π √L/g
- The longer the pendulum the longer the period, shorter the pendulum the shorter the period
25.2 Wave Description- Simple harmonic motion: The back and forth vibrating motion of a swinging pendulum.
- Sine curve: A curve whose shape represents the crests and troughs of a wave.
- Crest: One of the places in a wave where the wave is highest or the disturbance is greatest on the wave.
- Trough: One of the places in a wave where the wave is lowest or the disturbance is greatest to the opposite crest.
- Amplitude: The distance from the midpoint to the maximum crest of a wave or, from the midpoint to the minimum trough.
- Wavelength: The distance from the top of one crest to the top of the next one.
- Frequency: How frequently a vibration occurs
- Frequency= 1/period
- Period= 1/frequency
Examples:Kaitlyn's heart beats 70 times per minute what is the period and frequency of her heart's beats? Answer: Frequency=70 Period= 1 minute
In Pittsburgh there is an unsafe building that is 500 meters high. It oscillates in the wind with a period of 4.45 seconds. What is the frequency of the vibration? Answer: 1/4.45=.225 Hz
- Hertz: A unit of frequency
- Source of all waves is something that vibrates
25.3 Wave Motionhttp://www.science-class.net/Notes/Images_8th_Notes/Transverse-Wave.png
25.4 Wave Speed
- The speed of a wave depends on the medium through which the wave moves.
- Whatever the medium, the speed, frequency, and wavelength of the wave are related
- Wave speed= frequency * wavelength
- Low frequencies have long wavelengths and high frequencies have shorter wavelengths.
25.5 Transverse Waves· Transverse wave: Whenever the motion of the medium is at right angles to the way in which a wave travels.
25.6 Longitudinal Waves
http://clackhi.nclack.k12.or.us/physics/projects/experiments/1999/Deb%20&%20Liz/slin_com.gif
25.7 Interference
- Interference pattern: A pattern formed by the overlapping of two or more waves that arrive in the same place at the same time.
- Constructive interference: The addition of two or more waves when wave crests overlap.
- Destructive interference: Combination of waves where crest parts of one wave overlap through parts of another, resulting in a wave of decreased amplitude.
- Out of phase: Term applied to two waves for which the crest of one wave arrives at the same place and at the same time that a trough of the second wave arrives.
- In phase: Term applied to two or more waves whose crests and troughs arrive at the same place at the same time.
25.8 Standing Waves- Standing wave: Wave in which parts of the wave remain stationary and the wave does not appear to be traveling.
- Node: Any part of a standing wave that remains still.
- Antinodes: The positions on a standing wave where the largest amplitudes are.
25.9 Doppler Effecthttp://asms.k12.ar.us/classes/physics/GENERAL/CATHERIN/DOPPLER1.GIF
25.10 Bow Waves
· Bow wave: The v-shaped wave produced by a moving object on a liquid surface faster than the wave speed.
· Something can be supersonic if it travels faster than sound.
· Bow waves are created by a speed boat going through the water and is made by the overlapping of many waves crests.
http://media-2.web.britannica.com/eb-media/95/124895-004-BDC9E53F.jpg
25.11 Shock Waves
· Shock wave: A cone shaped wave produced by an object moving at supersonic speed through a liquid.
· Shock wave is produced by overlapping spheres that form a cone.
· Sonic boom: The sharp crack heard when the shock wave that comes from a supersonic aircraft.
Works Cited
Hewitt, Paul G. Conceptual Physics: With Expanded Technology The High School Physics Program. New York: Addison-Wesley Pub (Sd), 1999.